On Thu 16-08-18 21:44:02, Eric Sandeen wrote:
> The largest block size supported by isofs is ISOFS_BLOCK_SIZE (2048), but
> isofs_fill_super calls sb_min_blocksize and sets the blocksize to the
> device's logical block size if it's larger than what we ended up with after
> option parsing.
>
> If for some reason we try to mount a hard 4k device as an isofs filesystem,
> we'll set opt.blocksize to 4096, and when we try to read the superblock
> we found via:
>
> block = iso_blknum << (ISOFS_BLOCK_BITS - s->s_blocksize_bits)
>
> with s_blocksize_bits greater than ISOFS_BLOCK_BITS, we'll have a negative
> shift and the bread will fail somewhat cryptically:
>
> isofs_fill_super: bread failed, dev=sda, iso_blknum=17, block=-2147483648
>
> It seems best to just catch and clearly reject mounts of such a device.
>
> Reported-by: Bryan Gurney <bgurney@xxxxxxxxxx>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Thanks Eric, I'll take this patch through my tree for rc2.
Honza
> ---
>
> diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c
> index ec3fba7d492f..488a9e7f8f66 100644
> --- a/fs/isofs/inode.c
> +++ b/fs/isofs/inode.c
> @@ -24,6 +24,7 @@
> #include <linux/mpage.h>
> #include <linux/user_namespace.h>
> #include <linux/seq_file.h>
> +#include <linux/blkdev.h>
>
> #include "isofs.h"
> #include "zisofs.h"
> @@ -653,6 +654,12 @@ static int isofs_fill_super(struct super_block *s, void *data, int silent)
> /*
> * What if bugger tells us to go beyond page size?
> */
> + if (bdev_logical_block_size(s->s_bdev) > 2048) {
> + printk(KERN_WARNING
> + "ISOFS: unsupported/invalid hardware sector size %d\n",
> + bdev_logical_block_size(s->s_bdev));
> + goto out_freesbi;
> + }
> opt.blocksize = sb_min_blocksize(s, opt.blocksize);
>
> sbi->s_high_sierra = 0; /* default is iso9660 */
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
